Process for preparing halo-substituted diarylsulfones

ABSTRACT

A process for preparing diarylsulfone, the process comprising reacting chlorosulfonic acid with a mixture of (i) aromatic hydrocarbon represented by the formula ##STR1## wherein one of X and Y is a halogen atom and the other is a halogen atom or a hydrogen atom and (ii) aromatic sulfonic acid represented by the formula ##STR2## wherein X and Y are as defined above.

TECHNICAL FIELD

This invention relates to an improved process for preparingdiarylsulfones or more specifically, diarylsulfones having halogen onthe aromatic ring, such as 4,4'-dichlorodiphenylsulfone and the like.

Diarylsulfones are industrially useful compounds as intermediates forsynthesizing pharmaceuticals, dyes and the like or as materials forpreparing various types of synthetic resins, epoxy resin-curing agents,etc.

A variety of processes as given below are known for producingdiarylsulfones.

(1) A process in which benzene, chlorobenzene, toluene or like aromatichydrocarbon is reacted with a mixture of sulfuric anhydride and dimethylpyrosulfate (Japanese Pat. Nos. 301684; 305463; and 312809).

(2) A process in which aromatic hydrocarbon such as those mentionedabove and p-toluenesulfochloride, p-chlorobenzenesulfochloride or likearomatic sulfochloride are subjected to Friedel-Crafts reaction in thepresence of anhydrous iron chloride, anhydrous aluminum chloride or thelike (German Pat. No. 701954).

(3) A process in which aromatic hydrocarbon such as those exemplifiedabove is reacted with aromatic sulfochloride such as above in thepresence of benzenesulfonic acid, 4-chlorobenzenesulfonic acid, or likearomatic sulfonic acid (Japanese Examined Patent Publication No.5707/1975).

(4) A process in which aromatic hydrocarbon such as above and aromaticsulfonic acid such as above are subjected to condensation reaction usingphosphorus pentoxide or like phosphorus oxide-type dehydrating agent(Japanese Examined Patent Publication No. 24662/1968).

(5) A process in which reaction is conducted between aromatichydrocarbon such as above and aromatic sulfonic acid such as above at ahigh temperature of more than 200° C. (Japanese Unexamined PatentPublication No. 76834/1974 and U.S. Pat. No. 2593001).

(6) A process in which specific amounts of halobenzene compound andchlorosulfonic acid are subjected to reaction at less than 10° C. andthereafter a specific amount of halobenzene compound is further added tothe resulting reaction mixture, followed by heating of the mixture at40° to 60° C. (U.S. Pat. No. 2860168).

However, all of these processes have drawbacks to be remedied and remainunsatisfactory from commercial viewpoints. More specifically stated, theprocess (1) uses dimethyl sulfate having high toxicity and thus isimpractical because of the problems on operators' sanitation anddisposal of waste water. The processes (2) and (3) employ aromaticsulfochloride as the starting material which is difficult to obtain andwhich is prone to hydrolysis in handling and during storage, requiresreaction at a high temperature of more than 100° C. and gives productwith low purities. The process (4) entails reaction which continues overa period of about 24 hours at a high temperature of over 80° C., usually130° to 180° C. and results in the production of a product with lowpurities. The process (5) requires reaction at a high temperature ofmore than 200° C. and produces a product having low purities in lowyields. The process (6) needs a low-temperature reaction, provides aproduct, although with high purities, in yields as low as about 30%,necessitates a cooling device to maintain the reaction system at a lowtemperature of less than 10° C., usually -5° to 5° C. and involves acumbersome procedure due to the two-step reaction. In short, theseconventional processes suffer from the disadvantages with respect tostarting materials to be used, procedures involved, reaction efficiency,equipment, etc. and generally entail reaction at high temperatures, failto give a desired product with high purities in high yields and requirepurification of the reaction product using a solvent or the like toobtain a commercially acceptable end product.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide an improved process forpreparing diarylsulfones, the process giving a desired product with highpurities in high yields, using inexpensive and readily availablestarting materials and involving a simple procedure to be easily carriedout at a mild temperature in the vicinity of room temperature andcompleted in a short period of time without entailing a step or devicefor heating or cooling.

More specifically stated, the present invention provides a process forpreparing diarylsulfone, the process comprising reacting chlorosulfonicacid with a mixture of (i) aromatic hydrocarbon represented by theformula ##STR3## wherein one of X and Y is a halogen atom and the otheris a halogen atom or a hydrogen atom and (ii) aromatic sulfonic acidrepresented by the formula ##STR4## wherein X and Y are as definedabove.

According to the present invention, desired diarylsulfones can beproduced efficiently with considerably high purities in significantlyhigh yields by conducting a simplified, single-step reaction under mildconditions for a short period of time without using aromaticsulfochlorides which are difficult to obtain and which require specialcare in handling and during storage, dimethyl sulfate of high toxicityand the like. The reaction in accordance with the present inventionrapidly proceeds at ordinary temperatures and pressures, without using adevice for heating and cooling the reaction system, and produces adesired product with such high purities (over 99.5%) that the productthus prepared can be used with effectiveness for various purposeswithout being purified, subsequent to the reaction. Therefore, thisinvention is particularly suited to industrial application.

Specific examples of the aromatic hydrocarbons represented by theformula (I) and to be used as the starting material in the presentinvention are chlorobenzene, bromobenzene, fluorobenzene, iodobenzene,dichlorobenzene, dibromobenzene, etc. Preferred examples of usefularomatic sulfonic acids represented by the formula (II) arechlorobenzenesulfonic acid, bromobenzenesulfonic acid,dichlorobenzenesulfonic acid and the like which each correspond to theabove-mentioned aromatic hydrocarbons. It is generally desired to usearomatic sulfonic acids in the form of anhydride.

The present invention can be practiced usually by preparing a mixture ofthe aromatic hydrocarbon and the aromatic sulfonic acid and addingchlorosulfonic acid to the mixture for reaction. The aromatic sulfonicacid is mixed with the aromatic hydrocarbon in an amount of usuallyabout 0.3 to about 2 moles, preferably about 0.8 to about 1.2 moles, permole of the former. If the aromatic sulfonic acid is present in anamount far smaller than in the range, diarylsulfone is produced inreduced yields. The use of the acid in excess of the foregoing range islikely to provide an end product in decreased yields rather thanincreased yields. An appropriate amount of chlorosulfonic acid to beused ranges usually from about 0.8 to about 1.5 moles per mole of thearomatic hydrocarbon. The yield and the purity of diarylsulfone producedis affected by the amount of chlorosulfonic acid used. Below the range,reduced yields result, whereas above the range, no yield is enhanced butpurity is lowered due to production of a by-product in a larger amount.

The reaction according to the present invention favorably proceeds bymaintaining the reaction system at a temperature of less than 60° C.,usually about 10° to about 30° C. With the reaction at more than 60° C.,the yield of diarylsulfone obtained tends not to increase, ratherdecreasing as compared with the reaction at less than 60° C., althoughwith the result of the aromatic hydrocarbon observed as consumed. Thereaction at extremely low temperature entails a cooling device or thelike and is caused to continue for a prolonged period of time. Accordingto the present invention, the reaction is completed when the evolutionof hydrochloric acid gas has ceased, usually several hours after thestart of addition of chlorosulfonic acid. After the completion of thereaction, water is added to the reaction mixture and, when required, theunreacted aromatic hydrocarbon is separated and recovered bydistillation or like method, whereby diarylsulfone can be obtained as aprecipitate. From the filtrate left after the separation of theprecipitate can be recovered a portion of aromatic sulfonic acid whichcan be reused for the ensuing reaction of the present invention.

The diarylsulfone thus obtained generally has a considerably high purityof about more than 99.5% (according to liquid chromatography) and thuscan be used for various purposes without being purified. But the productmay be purified, of course, by conventional purifying procedure.

The present invention will be described below in more detail withreference to the following examples and comparison example.

EXAMPLE 1

A 211 g (1.1 moles) quantity of 4-chlorobenzenesulfonic acid was addedto 112 g (1 mole) of chlorobenzene and the mixture was cooled with waterwhile 123 g (1.1 moles) of chlorosulfonic acid was added to the mixtureat about 10° to about 20° C. over a period of 1 hour. After theaddition, the reaction mixture was stirred for 3 hours while beingmaintained at 20° to 30° C. The hydrochloric acid gas evolved during thereaction was continuously removed from the reaction system. After thetermination of the reaction, about 400 ml of water was added to thereaction mixture and 11.2 g (0.1 mole) of the unreacted chlorobenzenewas recovered by distillation. The separation of the precipitate formedgave 77 g of 4,4'-dichlorodiphenylsulfone in a yield of 60% (based onthe amount of the aromatic hydrocarbon as consumed, the samehereinafter). M.P. 148.5° to 149.5° C. Purity of 99.8% (according toliquid chromatography, the same hereinafter).

COMPARISON EXAMPLE 1

To 112 g (1 mole) of chlorobenzene was added 123 g (1.1 moles) ofchlorosulfonic acid at 10° to 20° C. After the addition, while beingmaintained at 20° to 30° C., the mixture was stirred for 3 hours tocomplete the reaction. A 0.1 mole quantity of the unreactedchlorobenzene was recovered in the same manner as in Example 1 and 32 gof 4,4'-dichlorodiphenylsulfone was obtained in 25% yield. M.P. 148.5°to 149.5° C. Purity of 99.8%.

EXAMPLE 2

The same procedure as in Example 1 was repeated by using 147 g (1 mole)of o-dichlorobenzene, 250 g (1.1 moles) of1,2-dichlorobenzene-4-sulfonic acid and 174 g (1.5 moles) ofchlorosulfonic acid and recovering 14.7 g (0.1 mole) of the unreactedo-dichlorobenzene, whereby 85 g of 3,3', 4,4'-tetrachlorodiphenylsulfonewas given in 53% yield. M.P. 176.5° to 177.5° C. Purity of 99.9%.

EXAMPLE 3

The procedure of Example 1 was followed with the exception of alteringthe amount of 4-chlorobenzenesulfonic acid used to 96 g (0.5 mole),giving 58 g of 4,4'-dichlorodiphenylsulfone in 45% yield. M.P. 148.5° to149.5° C. Purity of 99.8%.

EXAMPLE 4

A 194 g (1.1 moles) quantity of 4-fluorobenzenesulfonic acid was addedto 96 g (1 mole) of fluorobenzene and the mixture was cooled with waterwhile 123 g (1.1 moles) of chlorosulfonic acid was added at about 10° toabout 20° C. over a period of 1 hour. After the addition, the reactionmixture was stirred for 3 hours while being maintained at 20° to 30° C.The hydrochloric acid gas evolved during the reaction was continuouslyremoved from the reaction system. After the completion of the reaction,about 400 ml of water was added to the reaction mixture, and 9.6 g (0.1mole) of the unreacted fluorobenzene was recovered by distillation.Separation of the precipitate by filtration gave 65 g of4,4'-difluorodiphenylsulfone in 58% yield. M.P. 97° to 98° C. Purity of99.7%.

EXAMPLE 5

To 204 g (1 mole) of iodobenzene was added 312 g (1.1 moles) of4-iodobenzenesulfonic acid and the mixture was cooled with water while123 g of (1.1 moles) of chlorosulfonic acid was added thereto at about10° to about 20° C. over a period of 1 hour. After the addition, thereaction system was stirred for 3 hours while being maintained at 20° to30° C. The hydrochloric acid gas evolved during the reaction wascontinuously removed from the reaction system. After the completion ofthe reaction, about 400 ml of water was added to the reaction mixtureand 20 g of (0.1 mole) of the unreacted iodobenzene was was recovered bydistillation. Separation of the precipitate by filtration gave 123 g of4,4'-diiododiphenylsulfone in 58% yield. M.P. 201° to 202° C. Purity of99.6%.

We claim:
 1. A process for preparing a diarylsulfone, the processcomprising reacting chlorosulfonic acid with a mixture of (i) ahalogenated aromatic hydrocarbon represented by the formula ##STR5##wherein one of X and Y is a halogen atom and the other is a halogen atomor a hydrogen atom and (ii) a halogenated aromatic sulfonic acidcorresponding to said halogenated aromatic hydrocarbon (i) andrepresented by the formula ##STR6## wherein X and Y are identical to Xand Y of said halogenated aromatic hydrocarbon (i).
 2. A process asdefined in claim 1 in which the halogenated aromatic hydrocarbon isselected from the group consisting of chlorobenzene, bromobenzene,fluorobenzene, iodobenzene, dichlorobenzene and dibromobenzene and thehalogenated aromatic sulfonic acid is the correspondingly halogenatedaromatic sulfonic acid.
 3. A process as defined in claim 1 in which themixture of the halogenated aromatic hydrocarbon and the halogenatedaromatic sulfonic acid comprises about 0.8 to about 1.2 moles of thelatter per mole of the former.
 4. A process as defined in claim 1 inwhich the chlorosulfonic acid is used in an amount of about 0.8 to about1.5 moles per mole of the halogenated aromatic hydrocarbon.
 5. A processas defined in claim 1 in which the reaction is conducted at atemperature of 10° to 60° C.